Tension wrench



Sept. 23, 1941. J. M. HILL TENSION WRENCH Filed May 2l, 1938 Patented Sept. 23, 1941 UNITED STATES PATE-NT OFFICE 6 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government ior governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a torque indicating wrench capable of general use but especially designed for tightening of engine cylinder holddown nuts.

n assembling the cylinders of engines, particularly air-cooled radial engines, on the crank- 1 case sections, it is required that the cylinder hold-down nuts be tightened to a specified torque in inch pounds. They must not be tightened by ierking but rather by slowly and smoothly applying the proper torque. 1

It is, therefore, the main object of the present invention to provide a special torque indicating wrench for tightening hold-nuts to the correct torque in accordance with the requirements above set forth.

Additional and more specic objects of the in /ention are to provide a wrench of the type set 'orth which is simple in design, smooth in ac- '.ion, advantageous for use on aircraft engines n close places, accurate in indication, and capa- )le of economical manufacture.

'I'hese objects and advantages are attained by he novel construction, arrangement, and comination of parts hereinafter more fully described ind explained in connection with the accom- 3 anying drawing, wherein:

Figure 1 is a top plan View of the improved vrench.

Figure 2 is avertical section on line 2 2 of ligure 1.

Figure 3 is a horizontal cross section on line -3 of Figure 2. Figure 4 is a l of Figure 2.

Figure 5 isa horizontal cross section on line 5 of Figure 2.

Figure 6 is a view similar to Figure 1 but deloting the handle member and dial displaced pointer in indication o1 a toronal loading between the minimum and maxnum.

Figure 7 is a perspective view of the wrench ith parts thereof removed and with portions roken away to expose the torque spring asrmbly.

Briey, the improved wrench embodies a hanto the socket assembly horizontal cross section on line The helical spring I is housed within a cylinder or barrel 2 of appropriate length. At the end 3 of the barrel is a handle assembly including a cylindrical body 4 and a rod 5. The handle body has two end sections a and c and an intermediate section b preferred means.

At the end 1 of the barrel opposite to the handle end 3, is arranged the socket assembly which includes the socket-supporting member 8, together with its shank 9, and the nut-engaging member I0. Member 8 is a cylindrical body beyond the said end of the barrel and the sections b and c' enclosed within the latter. The barrel is dxed to the section b' by suitable means II capable of being removed to permit separation of the barrel and socket assembly when so desired. Section b' has a snug iit in the barrel-end 1 and is of a length to internally support and reinforce the same over a substantial area. Section c is of smaller diameter than section b and is a cylindrical projection, on the inner face of the latter. It is encircled by several of the coils at the adjacent terminal or socket end of the helical spring I, which, at the said end, is seated on and fixed to the projection manner as described and explained in connection with the corresponding projection c of the handle assembly. Section a' of the socket supporting member 8 is a carrier for the socket shank 9. The carrier and the shank may be a single integral unit or it may be composed of two separable parts. In the accompanying drawing, they are depicted as separable parts; the carrier 8 being provided with a hollow axial space or cavity I2 opening outwardly of its exposed end to receive the correspondingly shaped shank 9 which is firmly held therein by one or more screws I3. The shank has a squared end I4 to ilt the squared recess ln the nut engaging member or socket I8 which is retained on the shank by a conventional ball-and-spring lock I5. This construction and arrangement of the socket assembly is advantageous in enabling various types and sizes of sockets` to be used interchangeably with the socket supporting member 8.

In Figure 2 of the drawing, the wrench is shown applied to a cylinder hold down nut I6. When the handle body 4 is turned by pressure applied to the rod 5 a torque is transmitted, through the helical spring I in a twisting motion, to the nut I6 engaged in the socket I0. When the resistance offered by the nut is slight, or below the minimum of the range for which the wrench is designed, the nut and the wrench turn as a unit. But where the resistance offered by the nut is great or in excess of the minimum of the range of the wrench, the handle body 4 turns relatively to the barrel and the socket assembly which remains stationary with the nut until the torque force exerted by the twisting of the spring is sufficient to overcome the resistance of the nut. Cylinder hold down nuts are generally required to be tightened to a specific torque in inch pounds and in order that the wrench may be particularly adapted for this purpose it is provided with torque-indicating means.

The torque-indicating means includes a dial cup I1 fixed at the outer end of the handle body 4 and concentric with a narrow bore I8 extending axially through the body and the base of the cup. A transparent cover I9 is held in place on the cup by a flanged screw ring 28 as illustrated. Enclosed within the cup and fixed thereto by screws 2|, or other suitable means, is a fiat centrally apertured dial disk 22 having graduations thereon to give a reading of torque in inchpounds. The wrench may be designed to indicate torque over any desired range within reasonable limits but in the present instance the dial is shown graduated to cover a range approximately of 50 inch-pounds minimum to 400 inchpounds maximum. Suitably xed at its end 23 to the projection c' of the socket supporting member 8 and extending longitudinally and centrally of the spring I with its opposite end 24 within the dial cup is a long slender rod or shaft 25. As is apparent from Figure 1 of the drawing, this shaft 25 extends through the axial bore I8 c in substantially the same of the handle body 4 and also through the central orifice 5a of the hand lever 5 and the central aperture of the dial disk 22. The extension of the shaft through the 'central orifice of the hand lever prevents the latter from being displaced with respect to the head as long as this relation is maintained. Mounted on the end 24 of the shaft and projecting laterally thereof in cooperative relation with the graduated dial disk is an index hand or pointer 26. The shaft-end 24 is screw threaded to receive a nut 21 which is tightened against the pointer to holdl the latter rigid with the pointer shaft 25.

The helical spring is placed under initial tension corresponding to the minimum torque of the selected range by rotating the head 4 relative to the member 8 an estimated number of turns. 'Ihis minimum torque is substantially maintained by a stop built into the wrench and functioning above and below the registering range of the wrench to prevent excessive strain on the spring. This stop comprises a stop lug 28 screwed in an opening 28 in the side of the head section b and working in a circumferential slot 38 of a predetermined length formed in the side of the barrel 2. The dial 22 and the stop lug 28 are so correlated with the pointer 26 that when the lug is pressed against the end 3| of the slot by the force of the spring I, the pointer is slightly outside minimum graduation on the dial. 'I'his relation of the parts is illustrated in Figures l, 2 and 4 of the drawing from which it will be apparent that when the handle end of the wrench is turned' in a clockwise direction relative to the socket end thereof, the spring is further tensioned to exert a 'torque on the nut. The dial, being fixed to the handle body, is likewise turned relatively to the pointer so that the position of the latter with respect to the graduation of the dial at any given instant indicates the applied torque. When the handle body 4 is turned in the clockwise direction, the lug 28 is correspondingly shifted along the slot 38 and abuts the opposite end 32 of the latter when the pointer is slightly outside the maximum graduation of the dial. To tighten a nut, the wrench is turned in the clockwise direction in the manner just described and any turning force of the handle assembly above the registering range of the wrench is transmitted to the socket end thereof by the abutment of the lug 28 against the end 32 of the slot and without any additional stress or strain on the helical spring. To back up or loosen a nut, the wrench is turned in the reverse or counterclockwise direction, In the latter case, however, the turning force of the handle assembly is transmitted to the socket end of the wrench by the abutment of the lug 28 with the end 3| of the slot and the loosening of the nut is accomplished, therefore, without any reverse twisting` or strain of the helical spring.

From the foregoing, it will be seen that the wrench is characterized by simplicity in design and absence of large and protruding parts such as would interfere with the proper use of the wrench in close places. It is smooth in action, without tendency to grab, and holds its calibration more satisfactorily than other types, such as .hydraulic types which may change through leaks and temperature variations and clutch types which may change through slippage due to oil or moisture collecting on the friction faces Various changes and substitutions in respect tc shape, size, dimensions, etc., of the parts of the wrench may be resortedto without departing from the principle and scope of the invention as defined in the following claims:

Having thus described the invention, I claim:

1. A torque registering wrench having in combination a shaft, a handle member turnable on the said shaft, a socket-bearing member iixed to the shaft on one side of the handle member, an index fixed to the shaft on the opposite side of the handle member, elastic torque-transmitting means coupling the handle member with the socket-bearing member, a scale fixed to the handle member in cooperative relation with the index, and coacting means on the said handle and socket-bearing members functioning irrimediately above and below the registering range of the wrench to limit the relative movement of the said members to one direction only.

2. A torque indicating wrench having in combination a helical spring, a socket assembly on one end of the spring for engagement with an object to be turned, said socket assembly including a spindle extending axially of the spring, a handle assembly on the other end of the spring for applying a torsional twist thereto, said handle assembly including a body having an axial bore through which the said spindle extends and a transverse bore intersecting the said axial bore, a rod in said transverse bore and extending outwardly of the said body, said rod having a transverse orice therein for the extension of the said spindle therethrough, and means for retaining the body upon the said spindle.

3. A tension Wrench having, in combination, a barrel, a substantially solid member at cach end oi the barrel, each member having a snug t in the barrel for a distance to internally support and reinforce the latter over a substantial area and at its inner end having a short central projection in laterally spaced relation to the enclosing wall of the barrel, one of said members vbeing iixed to the barrel and the other member being free to be turned within the barrel, a helical torque-transmitting spring enclosed within the barrel with several of the coils at onev end encircling and fixed to the central projection of the fixed member and several of the coils at the other end similarly arranged with respect to the corresponding projection of the turnable member, a nut-engaging element secured to the iixed member of the barrel, and hand grips on the turnable member of the barrel for turning the same for applying a torsional twist to the said spring.

4. A tension wrench comprising coaxial members relatively rotatable about their common axis, means on one of said members for engagement with an object to be turned, means on the other of said members by which rotational movement may -be imparted thereto, a torsion spring between and positively connected to each oi the said rotatable members, said spring be. ing pre-wound to a predetermined torque load, a calibrated dial on one of the rotatable members having a minimum graduation indicating the pre-loading on the spring and having a maximum graduation indicating a maximum allowable loading on the spring, an index on the other rotatable member in cooperative relation with the said dial, and means for limiting relative movement between the members including stop means provided on the members to operate at each end of the allowable relative movement to prevent any relative movement between the members tending to load the spring beyond the maximum amount of allowable load indicated by the maximum graduation of the scale or tending to decrease the load on the spring below the minimum graduation of the said scale.

5. A torque registering wrench comprising a hollow cylinder having a circumferential slot adjacent one end thereof, a handle member journaled in the said end of the cylinder to be rotated relative thereto and having a stop lug projecting into the said slot adapted by its abutment with either end of the slot to prevent relative turning movement between the cylinder and the handle member, a nut engaging member fixed to the cylinder at the other end of the latter, a flexed helical torque transmitter spring connecting the handle member with the nutengaging member and under a predetermined initial torsion normally holding the cylinder and nut-engaging member angularly displaced relative to the handle member with the said stop lug in abutment with one end of the said slot, a calibrated dial on one of the said members having a minimum graduation corresponding to the predetermined initial torsion of the spring and having a maximum graduation corresponding to the higher limit of a selected scale range, and an index on the other member in cooperative relation with the said dial, seid dial and index being so correlated with the lug and slot that when the lug abuts one end of the sloty the index coincides with the minimum graduation on the scale and when the lug abuts the other end oi the slot the index is on. the maximum graduation on the dial whereby to prevent varying the load on the spring beyond the limits of the scale.,

6. A torque measuring wrench having, in combination, a pair of axially spaced relatively rotatable members, one of said members being adapted to be engaged with a piece of work and the other member being adapted to have rotational movement imparted thereto, an axially disposed shaft carried by one of said members and rotatably extending through the other of said members, a helical torque-transmitting spring having one end connected with one of said members and its other end connected with the other of said members so that it tends to hold said members in axially spaced relation, said spring being pre-wound to a predetermined torque load, torque-indicating means including a calibrated element carried by said other member and having minimum and maximum graduations indicating the pre-loading and the maximum allowable loading on the spring and an indicator element operatively connected with the said shaft and disposed in registering relation to the calibrated element, and a coupling element securd to one of the relatively rotatable members and rotatably interlocked with the other of said rotatable members to prevent axial separation of the said rotatable members while restricting relative rotation oi' said members to within the indicated load range of the torque indicating means` JAMES M. I-IIIL. 

